In recent years, interest in energy saving increases and an Energy Management System (EMS) is getting a lot of attention as a control apparatus to perform power management by the power consumer. The control apparatus to perform the power management by the house is called as a Home Energy Management System (HEMS).
The EMS communicates with the equipment such as a distributed power source, a home electric appliance, and a sensor provided in the consumer using a short-range communication network (PAN: Personal Area Network) provided in the consumer.
Such a short-range communication network does not depend on an infrastructure network, that is, an autonomous distributed radio network. A ZigBee (ZigBee (registered trademark)) is known as one of communication protocols to realize this network (for example, see Patent Literature 1).
In ZigBee, a physical layer (PHY layer) and a Mac layer apply IEEE802.15.4, and a network layer (NWK layer) and an application support sub-layer (APS layer) apply a protocol formulated in ZigBee Alliance (a ZigBee protocol).
Further, in a ZigBee network, a device managing the network is called as a ZigBee coordinator (ZC), a relaying (routing) device is called as a ZigBee router (ZR) and an end device is called as a ZigBee end device (ZED). Therefore, the EMS comprises a ZigBee module corresponding to the ZC, each of the equipment such as the distributed power source, the home electric appliance, and a sensor comprises the ZigBee module corresponding to the ZR or the ZED.